This invention relates to, for example, an apparatus, method, and system for safely utilizing a rechargeable energy device.
Some energy storage devices such as, for example, thin-film solid electrolyte batteries or capacitors may be susceptible to damage when exposed to continuous or momentary influxes of high charging voltages. Batteries may, for example, be damaged if discharged beyond their design parameters.
Over-charge protection relates to a condition when a relative large voltage is allowed at the input to a battery cell or capacitor for an any time period. In order to protect against overcharge, device protection circuits may be used to monitor the current and voltage and inhibit battery charge when overcharge is sensed.
Under-voltage conditions also have the potential to damage the energy storage device. In a battery, for example, during an under-voltage condition the battery may discharge beyond the point of recovery.
Thus, a need exists to protect an energy storage device from over-charge and/or over-discharge conditions.
To implement the functionality mentioned above, the current available art may generally require power consumption from the device to be charged for the over-charge circuitry. That is, the existing art may involve circuits using quiescent current from the battery or capacitor to be charged. Also, current known art may involve switching to disable the charging source when an overcharge condition exists despite the absence of a charging source or similar energy being present. Other known over voltage control circuits use voltage regulation schemes that clamp input power to a known voltage prior to input to the energy storage device to be charged. These may use a significant amount of power either from the rechargeable device or from input power to the system. These mechanisms may not be ideal because, for example, they increase the amounts of leakage current taken from the battery or capacitor to be charged or use input energy that may be otherwise allowed into the rechargeable energy storage device.
Additionally, a demand exists for an electronic device that, for example, does not require excess storage device requirements and may be able to gather energy efficiently, even including very trace amounts of energy, without, for example, damage during operation or the recharging process, either by over-voltage or under-voltage.
Further, there is a perceived need for an over-voltage and/or under-voltage protection circuit that, for example, does not operate using significant quiescent current from the energy storage device, nor essentially load or waste input charge energy with regulation when regulation is not necessary, thus consuming less energy from both the rechargeable energy storage device and the available input charge energy.